The major goals of the proposed work are to further elucidate diaphragm-rib cage interaction and the mechanism of load compensation and to provide a rational approach to rehabilitation of patients with chronic obstructive pulmonary disease. Based on review of recent advances in chest wall mechanisms, a modification of the theory of diaphragm-rib cage interaction is proposed. In order to test this and other theories of interaction, the contributions of intercostal muscles and diaphragm to chest wall motion based on analysis of the pressure-volume relationship of rib cage and abdominal compartments will be correlated with the muscle activities assessed by electromyography. We have also formulated a preliminary working concept of respiratory muscle control and recruitment which allows us to predict the response of the respiratory muscle-bellows system to 1) inspiratory resistive loading plus imposed respiratory rhythm at a lower rate, and 2) to weight loaded on rib cage and on abdomen. These predictions will be tested based on analysis of pressure-volume relationship of rib cage and abdominal compartment and EMG activity. An attempt will be made to rehabilitate patient with COPD by restoring the diaphragmatic function and strengthening the respiratory muscles by training. The efficacy of abdominal pneumobelt and lung resection will be evaluated as therapeutic measures.